Axis (axial) - central lobe running the length of the trilobite body
Cephalon (cephalic) - frontmost part of the trilobite; ie. the head
Ecdysis - shedding of the exoskeleton
Enrollment - bending and rolling up of the body to enclose vunerable organs on the trilobites underside
Furrow - linear groove, often defines adjacent convex features such as the lobes of the glabella
Gena - cephalic shell of the cephalon surrounding the glabella, usually divided by sutures
Genal angle - angle formed by the meeting of the side and rear margins of the cephalon
Genal Spine - a spine anywhere on the gena of the cephalon
Glabella - middle part of the cephalon, usually convex and lobed
Gonatoparian - facial sutures ending at the tip of the genal angle
Holochroal - eyes with compound lenses all directly in contact, covered by a single, smooth continuous corneal surface
Hypostome (hypostomal) - a piece of exoskeleton on the underside of the cephalon, thought ot be a mouthpart
Pleura (pl. Pleurae)(pleural) - side part of the thoracic segment or non axial part of the pygidium
Proparian - facial sutures ending forward of the genal angle
Pygidium (pygidial) - hindmost section of the trilobite composed of fused segments, its separated from the thorax by an articulation
Rostral Plate - middle portion of the anteriormost edge of the cephalon, typically where the hypostome attaches
Schizochroal - eyes with compound lenses, each with a separate cornea, separated from each other by deep scleral walls with the membrane extending downwards into the sclera
Spinose - bearing spine or spines
Suture - linear break in the exoskeleton, typically along which parts separate during molting
Thorax (thoracic) - middle, segmented body portion between the cephalon and the pygidium
Tuberculate - bearing tubercules or simmilar sculpturing on the outer exoskeleton

Author: Sarah Vinnell
Last updated: 21/11/05
Return to Fossil groups home page

Websites produced by students on the MSc Palaeobiology programme in the Department of Earth Sciences at the University of Bristol for academic year 2005-6